This not only applies to WoW and Blizzard, but also to many other games.

In the meantime, i got a Blizz whisper when my toon in BG AV and said - "do not use any illegal software to process game or u will get ban. " something like that.
So i report to GM and send them the screen capture and waiting their reply.
In-game messages from Blizzard/GMs have the Blizzard logo. If it doesn't have the logo, it's just somebody trying to be a jerk.

Blizzard, and pretty much the rest of these companies these days, are well aware of multiboxers, dual-boxing.com, ISBoxer and other multiboxing software products. And they are not interested in banning you for multiboxing, because it is not against the rules, and where exactly should they draw the line? Tons of people have multiple accounts. Simply put, the rules that apply to multiboxers are the same rules that apply to everyone else: no botting, no hacking, no cheating, no exploiting, no harassment, etc. So if you're being a dick to everyone you meet, or if you spawn camp with your mass of toons, etc eventually you're probably going to get in trouble for harassment and potentially banned -- but not just for multiboxing. This is why the "Is ISBoxer allowed?" page suggests you be a good citizen. Game companies so far have agreed.